Following the Shugart standard, selections for 4 drives (DS0..DS3) are available on a single interface. The drives had to be jumpered accordingly. Hardware-wise the PC floppy controller also supports this. But as the original housing only allowed two (full height) drives, the controller thus split the interface onto two (proprietary) connectors: one PCB header for up to two internal drives, and a DB37 for two external drives (separate housing). Each features only two DS signals (DS0/1 internal, DS2/3 external).
To simplify installation, IBM invented the twisted floppy cable, swapping the two select lines between the PCB connectors for the drives. This took away the need for individual jumpered drives. IBM drives were always set to DS1 (*1), and addressing was done via the connector used. In fact, there's another (logical) twist, as the outermost connector is always the 'first' drive. This is due to the termination needed / built in (*2) on (early) 5.25 inch drives.
Nice design for simplifying upgrades, but it complicates more sophisticated installations - like 4 half height drives within the original case.
With an original controller it's no problem to have 4 drives. Just cable work.
Clones with integrated/on-board controller often had two pin headers for floppies, so 4 internal drives could be used (*3). Later again the second connector got often dropped, so more recent machines only supported two drives. You may want to check the manual for your machine.
Also, with 3.5 inch drives becoming standard, clone manufacturers invented the 4 connector type cables you mentioned. These are not meant to support 4 drives, but rather offer the choice to have either for each position. Usually (*4) the connectors are paired in a way making it physically impossible (*5) to add more than one drive for each position.
Edit: Here is a nice page showing the development in detail.
*1 - It's not that easy, since IBM did use drives with different labeled selector blocks. With the ones labeled DS0..DS4, DS1 is the right selection, while on drives with a DS1..DS4 labeling, DS2 needs to be selected.
*2 - Termination is another issue to take care of, at least for 5.25 inch drives. Only the last (
A) drive needs one, while the second must not have it. It's a resistor array, usually looking like a socketed IC often of yellow/brownish colour, but sometimes also like a SIL package. 3.5 inch drives do not need to be changed here, as their behaviour is like automatic. It can be added as A or B without changing anything.
*3 - Be careful, some had two pin headers, but each only supporting one drive - basically moving the cable twist onto the motherboard to save on cabling costs by only needing to supply two straight cables with single connectors (and no 5.25 support).
*4 - As so often with Taiwanese creativity, there are cables made without that restriction in mind.
*5 Well, almost - never underestimate users with a dedication to add a third drive